Cleaning, Inspection and Replacement

TM 10-3930-621-34

(4) With housing in vise, control end up, unscrew

check seat (45) with 3/16 inch hex wrench.

9-5. Assembly and Adjustment

(5) Remove housing from vise and up end it.

a. General. Refer to figure 9-1 with applicable figures

Tapping it lightly with palm of hand, allow check valve

when assembling and adjusting.

seat (45), ball (46), and spring (47) to fall into other hand.

b. Control Assembly.

(6) Remove centering pin (41) from control spool

(1) Install clean wooden block in vise to provide

and sleeve.

platform for assembly operations.

(7) Push inside lower edge of spool (50) so spool

(2) Place housing (48) on wood platform and

moves toward splined end and remove spool carefully

drop check valve spring (47) into check hole with large

from sleeve (49).

end down.

(8) Push the centering spring set (42) out of

(3) Drop check ball (46) into check hole making

spring slot in spool (50).

sure it rests on top of small end of spring (47).

9-4. Cleaning, Inspection and Replacement

(4) Place check valve seat (45) on 3 / 16 inch

a. Clean all parts with cleaning compound, solvent (P-

hex wrench and screw into a check hole so machined

S-661). Cleaning may be done during disassembly and

counterbore of seat is towards ball (46).

parts set to dry on clean paper towel.

(5) Lower wood platform in vise and place

b. Inspect all moving parts to make sure they have not

housing (48) on platform control end up. Clamp vise

been scored or damaged by dirt particles. Smooth

jaws lightly across housing port surface.

burnished surfaces are normal in many areas. Any

(6) Torque seat (45) to 150 inch-pounds and test

slightly scored parts may be cleaned by hand rubbing

ball (46) action by pushing against it with small, clean

with 600-grit abrasive paper.

pin.

c. Prepare all surfaces of control assembly for

Note. Ball need not be snug against seat to

assembly as follows:

function properly.

(1) Place a piece of 600-grit abrasive paper face

(7) Carefully install the spool (50) into the sleeve

up on a piece of plate glass or similar material.

(49). Be sure that spring slots of both spool and sleeve

(2) Clean the ends of the star gear first to

are at the same end. Rotate spool carefully while sliding

remove any sharp grit from the paper which could

parts together. Test for free rotation.

produce scratches.

Caution: Spool must rotate smoothly in

(3) Clean both sides of the ring gear, both sides

sleeve with finger tip force applied at splined end.

of the plate, the 14-hold end of the housing, and the flat

(8) Clamp wooden platform in jaws, set control

side of the end cap.

spool and sleeve on platform and aline spring slots of

(4) Stroke each surface across the abrasive

both.

several times and check the results. Any small bright

(9) Stand control spool and sleeve on end and

areas indicates a burr which must be removed. When

insert a flat tool through slots of both parts.

polishing the parts, hold them as flat as possible against

(10) Position three pairs of centering springs

the abrasive. After 6 to 10 strokes across the abrasive,

(42), or two sets of three each, on bench so ex- tended

check the part to see if it is polished. After each part is

edge is down and center section is together.

polished, rinse clean in solvent, blow dry with air, and

(11) Install one end of positioned spring set (42)

place it where it can remain absolutely clean until

on flat tool. Compress extended end of spring set and

assembly. d. Replace all packing and oil seals. Replace

push it into control spool and sleeve, with- drawing flat

all other parts as authorized.

tool at same time. See figure 9-4.

9-5